Auszug aus Wikipedia (20.05.2014)"An outflow boundary, also known as a gust front or arc cloud, is the leading edge of gusty, cooler surface winds from thunderstorm downdrafts; sometimes associated with a shelf cloud or roll cloud. A pressure jump is associated with its passage.[3] Outflow boundaries can persist for over 24 hours and travel hundreds of kilometers (miles) from their area of origin."Auszugsende

Auszug aus Wikipedia (20.05.2014)"A bow echo is a term describing the characteristic radar return from a mesoscale convective system that is shaped like an archer’s bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage. They can also become derechos."Auszugsende

Auszug aus Wikipedia (20.05.2014)"A wake low, or wake depression, is a mesoscale low-pressure area which trails the mesoscale high following a squall line. Due to the subsiding warm air associated with the systems formation, clearing skies are associated with the wake low. Once difficult to detect in surface weather observations due to their broad spacing, the formation of mesoscale weather station networks, or mesonets, has increased their detection. Severe weather, in the form of high winds, can be generated by the wake low when the pressure difference between the mesohigh preceding it and the wake low is intense enough. When the squall line is in the process of decay, heat bursts can be generated near the wake low. Once new thunderstorm activity along the squall line ends, the wake low associated with it weakens in tandem."Auszugsende

Auszug aus TheWeatherPrediction (22.11.2012)"A heat burst is a downdraft of hot and dry air that typically occurs in the evening or overnight hours. A heatburst is much more rare than a severe thunderstorm. Thus, the atmospheric conditions have to be just right for a heat burst to occur. Heat bursts usually happen in the evening or at night after thunderstorms are ending. Thus, a thunderstorm has a vital role. Two other characteristics are that the air must start its descent from fairly high up and the environmental air aloft needs to be very dry. Precipitation falling into very dry air aloft will cause the air to cool through latent heat absorption. If the air is very high aloft and the air is much more dense than the surrounding air then it will accelerate toward the surface. In the case of a heat burst, all the precipitation that cooled the air aloft has been vaporized. Therefore, the precipitation can no longer absorb latent heat. As this dense air accelerates toward the surface it rapidly warms at a dry adiabatic lapse rate compression. What must make a heat burst so rare is that this downdraft must reach extremely high velocities. Velocities must be high enough so that the momentum of the sinking air offsets the fact that it is becoming warmer in temperature and thus less dense than the environmental air it is falling into."Auszugsende

Auszug aus Wikipedia (20.05.2014)"In meteorology, lee waves are atmospheric standing waves. The most common form is mountain waves, which are atmospheric internal gravity waves. They are periodic changes of atmospheric pressure, temperature and orthometric height in a current of air caused by vertical displacement, for example orographic lift when the wind blows over a mountain or mountain range. They can also be caused by the surface wind blowing over an escarpment or plateau, or even by upper winds deflected over a thermal updraft or cloud street. The vertical motion forces periodic changes in speed and direction of the air within this air current. They always occur in groups on the lee side of the terrain that triggers them. Usually a turbulent vortex, with its axis of rotation parallel to the mountain range, is generated around the first trough; this is called a rotor. The strongest lee waves are produced when the lapse rate shows a stable layer above the obstruction, with an unstable layer above and below."Auszugsende